Solanum leucopogon
Citation:
Bol. Mus. Pará 4: 604. 1906.
Type:
PERU. Loreto: [Cerro de] Canchahuaya, 26 Oct 1898, J. Huber 1370 (lectotype, proposed in Stern thesis: MG [F neg. 1370!]; isotype (fragment): F! [F-602866])
Written by:
Stephen Stern
Habit:
Woody vine to 10 m. Stems moderately armed with recurved, yellow to orange roselike prickles, these 2-5 mm long, the base 1.5-3 x 0.5-1 mm, moderately to densely pubescent with red, porrect-stellate hairs, the stalks nearly sessile to 0.5 mm, multiseriate, the rays 5-7, 0.5-1mm, unicellular to multicellular, the midpoints 1-5 (8) mm.
Sympodial structure:
Sympodial units difoliate, the leaves usually geminate, those of a pair often slightly unequal.
Leaves:
Leaves simple, the blades 8-20 x 2-15 cm, ovate, chartaceous, slightly discolorous, dark green-brown adaxially, light green-brown abaxially, with both leaf surfaces moderately to densely pubescent, the adaxial surface with hairs like those of the stem but the stalk absent, the abaxial surface with white hairs like those of the stem, major veins 4-7 on either side of the midvein, the midrib abaxially often with few recurved prickles like those of the stem; base obtuse, often asymmetrical; margin unlobed to 3-6 obtuse lobes per side, the sinuses cut less than ¼ to 1/3 of the way to the midvein; apex acute; petioles 0.5-4 cm, moderately pubescent with hairs like those of the stem, sparsely to moderately armed with prickles like those of the stem, these often 2-ranked.
Inflorescences:
Inflorescences 3-7 cm, extra-axillary, unbranched with 5-15 flowers, the plants andromonoecious, with male flowers on young plants and hermaphroditic flowers on older plants, the axes moderately to densely pubescent with hairs like those of stem, generally unarmed; peduncle absent to 2 cm; rachis 1-6 cm; pedicels 5-15 mm in flower, 10-20 mm in fruit; nearly contiguous, spaced 2-4 mm apart.
Flowers:
Flowers heteromorphic, hermaphroditic (long-styeld) and staminate (short-styled) and the plants andromonoecious, 5 merous. Calyx 5-10 mm long, the tube 5-7 mm, the lobes 1-3 x 0.5-1 mm, triangular with acute to obtuse apices, often strongly recurved, moderately to densely pubescent with hairs like those of the stem, often with straight prickles 1-2 mm long; fruiting calyx 8-12 mm, not accrescent in fruit. Corolla 1-2.5 cm in diameter, charteacous, white, stellate, lobed nearly to the base, the lobes 5-10 x 2-4 mm, narrowly triangular, moderately to densely pubescent abaxially with white to red stellate hairs like those of the stem, sparsely pubescent adaxially. Stamens 4-8 mm; filaments to 1 mm, glabrous; anthers 4-8 x 1-2.5 mm, attenuate, tapering connivent, yellow, the base cordate, the apex obtuse, the pores apical, directed slightly introsely. Ovary sparsely pubescent with multicellular, uniseriate glandular hairs 0.2-0.4 mm long; style in functionally male flowers 2-3 x 0.5-1.5 mm, style in hermaphroditic flowers 7-10 x 0.5-1.5 mm, exserted beyond stamens, cylindrical, white, sparsely pubescent with glandular hairs like those of the ovary; stigma to 1 mm wide, cylindrical, green.
Fruits:
Fruit a leathery berry, 1.5-2.5 cm in diameter, globose, green when immature, orange to red when mature, glabrous.
Seeds:
Seeds 30-60 per fruit, reniform, brown, 2-2.5 x 1.5-2 mm, flattened, the surface netlike with many pits separated by small raised ridges.
Chromosome number:
Not known
Distribution:
Solanum leucopogon occurs in disturbed habitats including roadsides, forest gaps, and river sides in the eastern Andean foothills and adjacent lowlands from northern Ecuador through Peru to Cochabamba Department, Bolivia with some collections from the Amazon Basin in Peru and Ecuador at 200-2500 m.
Phylogeny:
Solanum leucopogon is a member of the Micracantha clade (section Micracantha) of the spiny solanums (Leptostemonum; Stern et al. 2011).
References:
Stern, S., M.F. Agra, & L. Bohs. 2011. Molecular delimitation of clades within new world species of the “spiny solanums” (Solanum subgenus Leptostemonum). Taxon.
Solanum leucopogon is most commonly collected in the eastern Andean foothills and adjacent lowlands from northern Ecuador through Peru. The cauline hairs of S. leucopogon make it among the most recognizable species in sect. Micracantha. The stems are typically densely pubescent with red, stellate hairs that have a short stalk (nearly sessile to 0.5 mm in length) but a greatly elongated midpoint (1-5 (8) mm in length). This species is sympatric through much of its range with S. pedemontanum; however, the latter species does not have the conspicuous cauline hairs and is recognizable by a dense white tomentum, especially on the abaxial leaf surfaces.
Solanum monachophyllum is weakly supported (67% BS, 1.0 PP) as the sister species of S. leucopogon (Stern and Bohs in prep). The range of these species possibly overlaps as both occur sporadically in the Amazon Basin; however, most collections of S. leucopogon are from the eastern foothills of the Andes while S. monachophyllum is more commonly collected in the Guiana Shield. Both species occur in disturbed habitats, however, S. monachophyllum is nearly exclusively found on river banks while S. leucopogon is common in light gaps in forests and roadside habitats. Morphologically S. monachophyllum is has nearly glabrous stems, small fruits, and much thinner corolla lobes and longer, narrower anthers than S. leucopogon.
The description of S. leucopogon in the “Boletim do Museu Goeldi (Museu Paraense)” does not specify the type locality. The collection at F has sparse material and is likely a fragment of the MG specimen; therefore, we have designated the MG specimen to be the lectotype. The name S. dimidiatum was used by Rafinesque (1840) for a North American species of spiny solanum making Sendtner's S. dimidiatum illegitimate. The only known specimen of the Sendtner name is at M where many of the collections used by Martius in “Flora Brasiliensis” are located, making this sheet the clear choice for lectotypification.
Huber chose the epithet “leucopogon” from the Greek “leuco-” meaning “white” and “-pogon” meaning beard in reference to the dense white pubescence found on the flower buds.